Mirror Courses
Highlight a course at the course selection screen, then hold L1 + L2 and press X.

Sound Test
While playing with 2 or more players press the four "Shape" buttons onthe other controller and you will hear the game's sound, one for each button.

Switch Hitting
When choosing a golfer, press L1 + R1 + X while choosing a golfer. This will change the golfer to opposite hand.

Unlock All Players and Courses
To do this you must remove all memory cards. Then, just before the screen flashes and the logo appears, on the SECOND Controller hold L1 + L2 + R1 + R2 then when the logo appears and is bouncing press Up, Up, Down, Up, Left, Right, Right, Left, Up, Up, Down, Up, Left, Right, Right, Left (still holding the 4 L & R buttons). If you did it right you will hear the sound of a club
(Wood) drive.

Alternate Clothing (Japanese version)
When the screen flashes before the Hot Shots logo appears during the opening sequence Press triangle, square, X, triangle, square, X, triangle, square, X.